Duplicate entries in different stores will be preserved, while in case of
true migration (detected account creation instead of password update) we
attempt to delete the user from the other authentication store.

Improved markup has been done similar to recommendation by Jun Omae, thanks!
Adds 1 msgid on catalog update. Hopefully I made the template more readable
too by shortening lines below the 80 chars limit.

It adds not only email address obfuscation but configurable full username
display too. To enable this in all content provided by TracForms
you'll need to add a dedicated configuration to your trac.ini as follows:

[forms]show_fullname=trueshow_fullname_position=change,macro,value

Caching the query done in env.get_known_users() is really nice,
only the CacheManager is available since Trac revision 8071 (0.12dev).
So this is kept optional to maintain compatibility with Trac < 0.12 .